In manure storage systems, manure from barn or livestock feed areas is delivered to a pit and mixed with water. The manure slurry is agitated and homogenized in the pit by a pump which can be raised and lowered in the pit and rotated to thoroughly mix or homogenize the slurry. The manure slurry can then be pumped from the pit by the pump to a manure storage tank or to a mobile spreader.
The conventional manure pump has a downwardly facing inlet through which the slurry is drawn into the pump, and because the slurry contains stringy and chunky materials, the pump incorporates a chopping mechanism to chop or comminute these materials.
A common type of motor-pump unit used in a manure system is a submersible type in which the motor is directly connected to the pump and is located within the pit and is normally submerged in the slurry. As the manure slurry can frequently contain hard objects such as rocks, cattle neck chains, barn cleaning paddles, and the like, these objects can cause jamming of the pump. To prevent damage to the drive mechanism in situations where the pump has jammed, a shear pin mechanism normally interconnects the motor shaft with the pump shaft and is arranged to fracture if excessive torque is applied to the shafts.